Time Conversion

#include <iostream>
using namespace std;

int main(void) {
    cout << "Time is seconds: ";
    int t_in_sec;
    cin >> t_in_sec;
    int H=t_in_sec/3600;
    int M=(t_in_sec%3600)/60;
    int S=(t_in_sec%3600)%60;;
    cout << "\nTime in hh:mm:ss = ";
    cout << H << ":" << M << ":" << S << endl;
    cout << endl;
    decision:
    cout << "Run Again(Yes/No)?" << endl;
    string y_n; cout << "->"; cin.sync(); getline(cin,y_n);
    if (y_n=="Yes" || y_n =="yes") {
        cout << endl;
        main();
    }
    else if (y_n=="No" || y_n=="no")
        cout << "\nThank You." << endl;
    else {
        cout << "\nF**k You! Yes/No only.\n" << endl;
        goto decision;
    }
    return 0;
}